WASHINGTON (Reuters) - Representative Seth Moulton, who mounted a long-shot bid for the 2020 Democratic presidential nomination, ended his campaign on Friday, warning that the party must now decide how far left it wants to move.

"But today, I want to use this opportunity ... to announce that I am ending my campaign for president," Moulton was to say at a speech before a Democratic National Committee meeting in San Francisco, according to remarks provided by his campaign.

"Though this campaign is not ending the way we hoped, I am leaving this race knowing that we raised issues that are vitally important to the American people and our future."

Moulton, a 40-year-old Iraq War veteran who represents a district in Massachusetts, failed to garner the support he needed to qualify for the Democratic debates. Without appearing in the debates, he had little hope of gaining traction.

Moulton stopped short of endorsing one of his rivals for the nomination, but said the race appears to have narrowed.

"I think it's evident that this is now a three-way race between (former Vice President Joe) Biden, (U.S. Senator Elizabeth) Warren and (U.S. Senator Bernie) Sanders, and really it's a debate about how far left the party should go," Moulton told the New York Times in an interview ahead of his announcement.

He built a political career by challenging the party's establishment including after the Democrats took control of the U.S. House of Representatives in g2018, when Moulton helped organize opposition to Representative Nancy Pelosi's bid to again become speaker of the House. He failed at that effort.